1. Technical Field of the Invention
The present invention relates to a method of producing a panel for an airbag of an automobile and the panel for the airbag of an automobile produced by the method, the panel being formed of an airbag cover (i.e., a cover body), made of a first synthetic resin, and the airbag cover or cover body being formed in a main body, the main body being made of a second, different synthetic resin, and the main body being, for example, an instrument panel or a door trim.
2. Discussion of Background
An airbag arranged in front of a front passenger seat of an automobile is stored on a rear side of the main body, the main body being, for example, an instrument panel or a door trim. When the airbag is operated, the airbag cover (i.e., cover body), mounted on the instrument panel, is opened and the airbag swells out in front of the instrument panel.
As shown in FIG. 51, an airbag cover 92 and an instrument panel main body 91 are formed as separate members, and the airbag cover 92 is fixed to the instrument panel main body 91 by a fixture (not shown). The airbag swells out in front of the instrument panel by rupturing a weak portion, such as a thin wall portion formed in advance in the airbag cover 92.
However, in the panel for the airbag having the structure described above, each of the instrument panel main body 91 and the airbag cover 92 are made in separate processes. Accordingly, a certain number of producing steps are required with respect to each of the instrument panel main body 91 and the airbag cover 92. Further, it is necessary to perform an assembly step to integrate both the members 91 and 92 with respect to each other and arrange a fixture. Accordingly, a problem exists in that the entire production cost of the airbag is increased.
This problem is similarly caused when a door trim, instead of the instrument panel, is set on a main body and the airbag cover is formed therein.
In consideration of such conventional problems, the present invention provides a panel for an airbag for an automobile which is produced easily and at a low cost, and provides a production method for the panel for the airbag of the automobile.
An embodiment of the present invention is a panel for an airbag of an automobile formed by integrally two-color molding a cover body, made of a first soft synthetic resin, with a main body, made of a second hard synthetic resin, the panel comprising:
a joint portion joined with the cover body provided around an opening portion formed in the main body,
wherein the joint portion constitutes an overlapping portion in which an outer peripheral edge of the cover body is overlapped as being arranged on the inner side of an opening edge of the main body and the overlapping portion is welded together in two-color molding the main body with the cover body.
In the present invention, the overlapping portion is arranged around the opening portion (an airbag swelling-out portion) of the main body, such as the instrument panel, in which an outer peripheral edge of the cover body (airbag cover) is overlapped as being arranged on the inner side of an opening edge of the main body. Therefore, neither a fixture, for connecting both the members, nor a connecting step, are required. Thus, in accordance with the present invention, the number of production steps and cost can be greatly reduced compared with a conventional product in which the cover body and the main body, such as the instrument panel, are separately formed.
With respect to the above-described embodiment of the present invention, it is preferable that the synthetic resin of the main body is a hard synthetic resin and the synthetic resin of the cover body is a soft one. Thereby, a rupturing operation of the cover body, which swells out of the airbag, can be smoothly performed by the soft synthetic resin, and the main body, such as the instrument panel, can maintain an excellent rigidity due to the hard synthetic resin.
As a particular means for improving joining strength of both the members in the overlapping portion, for example, it is preferable that a concavo-convex portion, having a serrated shape or a downwardly convex shape, is formed on a lower face of the main body in the overlapping portion as in an embodiment of the present invention. This constitution utilizes a so-called anchor effect yielded from a part of the synthetic resin of the cover body biting into a concave portion of the concavo-convex portion of the main body at a molding time of the cover body. The joining strength of both the members is improved by this anchor effect.
Further, distortion can be prevented at the time of molding a peripheral edge of the opening portion of the main body. Namely, when the cover body is molded, after the molding of the main body, the concavo-convex portion of the overlapping portion becomes resistance to an injection force of a material for molding the cover body. Therefore, no peripheral edge of the opening portion of the main body is distorted due to the injection force which pushes on the overlapping portion of the main body.
In each of the above two means, the joining strength of the main body and the cover body can be improved by an easy method and a simple structure.
Further, as in an embodiment of the present invention, it is preferable that a surface of a periphery of the cover body has a step portion backing to a rear surface of the cover body and facing the edge of the opening portion of the main body, thereby, a groove portion, having a closed curve shape, is formed in a boundary portion of an end portion of the opening portion of the main body in the cover body, and a thin wall portion, which ruptures, and a non-thin wall portion, which does not rupture at the operating time of the airbag, are formed along the groove portion in the cover body in a single line shape or a shape of plural continuous lines.
In this case, in a portion continuously connected to the groove portion, it is possible to easily form the thin wall portion thinner than the thicknesses of wall portions in the other portions. The thin wall portion ruptures earlier than peripheral portions when pressure is applied to this thin wall portion, and thus the thin wall portion practically becomes a rupturing portion of the cover body when the airbag is operated.
The boundary portion of the cover body and the main body can be easily observed because of the groove portion, and an excellent appearance in design may be also given depending on a shape of groove shape.
When the thin wall portion ruptures and the cover body is opened, it is preferable that the shape of a line forming the thin wall portion and the shape of a line forming the non-thin wall portion are set onto the cover body such that the non-thin wall portion becomes a rotating central axis of an opening movement of the opening portion of the cover body.
In this case, when the airbag is operated and the thin wall portion ruptures, a turning moment, with the non-thin wall portion as a rotating center, is applied to a ruptured cover portion and the cover body is easily opened. Accordingly, resistance to the airbag swelling-out is reduced and the airbag easily swells out.
For example, a combination of the shape of the line forming the thin wall portion and the shape of the line forming the non-thin wall portion, so as to set the non-thin wall portion on the rotating central axis of the opening movement of the opening portion of the cover body as mentioned above, is constructed as will be described with respect to a particular embodiment of the present invention in more detail below.
For example, as in an embodiment of the present invention, the non-thin wall portion is formed into a shape of one transverse line on an upper or lower side of the cover body, and the thin wall portion is formed in a U-shape (i.e., a quadrilateral shape with one side opened) along a groove portion in three directions except for the line forming the non-thin wall portion (see FIG. 2). Thus, a cover portion having the quadrilateral shape with one side opened is easily opened with the non-thin wall portion of the line shape as a rotating center.
Further, as in an embodiment of the present invention, the non-thin wall portion is formed into a shape of one transverse line on an upper or lower side of the cover body and the thin wall portion is formed along an entire periphery of the groove portion such that a line forming the non-thin wall portion is included in an inner side (see FIG. 9).
In this case, as described later, it is preferable that the cover body is connected to an airbag case through a rib. Although the thin wall portion is formed into a shape of a closed curve, the cover is not scattered, due to being released from restriction when the airbag is operated, even when the thin wall portion having the closed curve shape is entirely ruptured throughout its periphery, since the cover body is connected to the airbag case through the rib.
With respect to advantages of this construction, the thin wall portion of the closed curve shape is entirely ruptured throughout its periphery, and the cover body is separated from the main body as the cover body is connected to the airbag case through the rib. Accordingly, no stress is applied to the main body by the operation of the airbag in its operation. Further, there are no situations in which the main body is ruptured and a ruptured portion is possibly scattered.
As in an embodiment of the present invention, the non-thin wall portion can be formed into a shape of one transverse line on each of upper and lower sides of the cover body, and the thin wall portion can be formed into a shape of one longitudinal line on each of left-hand and right-hand sides of the cover body. A second thin wall portion, which is not formed along a groove portion, is formed into a shape of one transverse line in a central portion of the cover body. The entirety of the first and second thin wall portions can be formed in an H-shape (see FIG. 10).
In this case, the second thin wall portion, provided at the center of the cover, is ruptured and the cover is opened in two directions so that resistance of the cover to the airbag swelling-out is further reduced.
As in an embodiment of the present invention, the non-thin wall portion is formed into a shape of one transverse line on each of upper and lower sides of the cover body, and the thin wall portion can be formed along an entire periphery of a groove portion such that a line forming the non-thin wall portion is included in an inner side. Further, a second thin wall portion, which is not formed along the groove portion, is formed into a shape of one transverse line in a central portion of the cover body. The entirety of the first and second thin wall portions can be formed in a shape in which two quadrilaterals are lined up (see FIG. 14).
As a result, effects similar to those in one of the embodiments of the present invention described above can be obtained. Further, since the second thin wall portion, formed at the center of the cover, is ruptured, resistance to the airbag swelling-out is further reduced. In this case, as described later, it is preferable that the cover body is connected to the airbag case through the rib. Thus, the cover can be prevented from scattering when the airbag is operated.
Further, as in an embodiment of the present invention, the non-thin wall portion can be formed into a shape of one longitudinal line on each of left-hand and right-hand sides of the cover body, and the thin wall portion can be formed into a shape of one transverse line on each of upper and lower sides of the cover body. A second thin wall portion, which is not formed along a groove portion, is formed into a shape of one longitudinal line in a central portion of the cover. The entirety of the first and second thin wall portions can be formed in an H-shape (see FIG. 15).
As a result, operating effects, similar to those in one of the embodiments of the present invention described above, can be obtained.
Further, as described with respect to an embodiment of the present invention, the non-thin wall portion can be formed into a shape of one longitudinal line on each of left-hand and right-hand sides of the cover body, and the thin wall portion can be formed along an entire periphery of a groove portion such that a line forming the non-thin portion is included with an inner side. Further, a second thin wall portion is not formed along the groove portion, but is formed into a shape of one longitudinal line in a central portion of the cover body. The entirety of the first and second thin wall portions can be formed in a shape in which two quadrilaterals are lined up (see FIG. 17).
As a result, operating effects similar to those in one of the embodiments of the present invention described above can be obtained. In this case, as described later, it is also preferable that a rib, for a connection with the airbag case, is arranged in the cover body.
Namely, as described with respect to an embodiment of the present invention, it is preferable that the rib is projected in the non-thin wall portion and connected to the airbag case through a connecting member.
Since the rib is arranged, a portion near this rib is reinforced and the non-thin wall portion, having the rib, can be reliably set to a rotating center of an opening movement when the cover body opens.
Further, since the rib is connected to the airbag case through the connecting member, it is possible to reliably prevent the cover body from being separated from the airbag case and scattered when the airbag is operated.
Next, the embodiment of the present invention is a panel for an airbag of an automobile formed by integrally molding a cover body, made of a synthetic resin, with a main body, made of another synthetic resin, the panel comprising:
a joint portion, joined with the cover body, provided around an opening portion formed in the main body, wherein the joint portion constitutes an overlapping portion in which an outer peripheral edge of the cover body is overlapped as being arranged on the inner side of an opening edge of the main body, and the opening portion formed in the main body is mechanically connected to an outer peripheral edge of the cover body. This mechanical connection, for example, can be achieved by means of caulking and a fitting portion.
In this case, since the main body and the cover body are mechanically connected to each other by, for example, caulking, there are no restrictions in which compatibility is required in a synthetic resin material used in the main body and the cover body compared with a conventional connection using, for example, melt-bonding.
Next, an embodiment of the present invention resides in a panel for an airbag including:
a cover body comprising a first synthetic resin material;
a main body comprising a second synthetic resin material compatible with the first synthetic resin material, formed by two-color molding after forming the cover body; and
a deformation restricting portion provided at the outer peripheral edge of the cover body and engaged with a mold face,
wherein the main body comprises an opening portion which is closed by the cover body; and
wherein the deformation restricting portion restricts deformation of the cover body caused by a molding pressure which acts at a molding time of the main body.
When the main body is two-color molded with the cover body in a semisolid state within the mold, a large molding pressure acts on the outer peripheral edge of the cover body. In this case, since the cover body is engaged with the mold face because of the deformation restricting portion, no cover body is deformed even when the molding pressure acts on the cover body. This is particularly effective when a soft material is used as a material of the cover body.
Further, as in an embodiment of the present invention, it is preferable that the deformation restricting portion is constituted of a convex strip having an angular cross-section or a concave groove.
In this case, the cover body and the mold can be easily engaged with each other by the convex strip or the concave groove of the cover body, and a concave groove or a convex strip formed on the mold face and corresponding to the convex strip or the concave groove of the cover body. Therefore, it is possible to reliably prevent the outer peripheral edge of the cover body from being retreated, deformed or the like.
Further, an embodiment of the present invention resides in a panel for an airbag including:
a main body which has an opening portion comprising a first synthetic resin material;
a cover body comprising a second synthetic resin material compatible with the first synthetic resin material, formed by two-color molding after forming the main body; and
a deformation restricting portion provided at the periphery of the opening portion and engaged with a mold face,
wherein the opening portion of the main body is closed by the cover body; and
wherein the deformation restricting portion restricts deformation of the cover body caused by a molding pressure which acts at a molding time of the main body.
In this case, when the cover body for closing a swelling-out port of the airbag is molded by two-color molding within this swelling-out port with respect to the main body in a semisolid state inside of the mold, a large molding pressure acts on a main body portion at a peripheral edge of the airbag swelling-out port. Here, since the main body is engaged with the mold face by the deformation restricting portion, the main body is not deformed even when the molding pressure acts thereon. Accordingly, there is no problem that a shape of the peripheral edge of the airbag swelling-out port is shifted from its predetermined shape and becomes wavy.
Further, as in an embodiment of the present invention, it is preferable that the deformation restricting portion is a convex strip having an angular cross-section or a concave groove.
Also in this case, the main body and the mold can be easily engaged with each other by the convex strip or the concave groove of the main body, and a concave groove or a convex strip formed on the mold face and corresponding to the convex strip or the concave groove of the main body. Therefore, deformation of the main body, such as wavy deformation, can be reliably prevented.
Next, an embodiment of the present invention resides in a panel for an airbag of an automobile formed by integrally molding a cover body, made of a synthetic resin, with a main body, made of another synthetic resin, and providing a thin wall portion which ruptures when the airbag is operated:
wherein the main body and the cover body are integrally molded by one-color molding;
wherein a crack preventing layer is provided on a rear surface of a general portion, which is a portion not including the thin wall portion of the cover body; and
wherein the crack preventing layer prevents cracks of the general portion.
For example, the crack preventing layer can be achieved by joining a net made of polyamide (PA) and such with the rear face of the cover body in insert molding.
In this case, the main body and the cover body, for closing an opening portion of the main body, are integrally molded by one-color molding and are produced by the synthetic resin material. There is no discontinuity caused by the difference between materials in a boundary portion of the main body and the cover body so that an external appearance of the panel is improved. Further, since the main body and the cover body are integrally molded by one-color molding, producing and assembly steps are reduced.
Further, since the crack preventing layer is formed on the rear face of the general portion of the cover body, no general portion of the cover body formed by the synthetic resin material is cracked, so as to form broken pieces, when the airbag inflates.
Further, as in an embodiment of the present invention, it is preferable that a rib projects into the cover body on the rear face of a portion in which no thin wall portion is formed. It is also preferable that a connecting member made of a metal and extending from a side of the main body is connected to the rib, and a projection is formed on a surface of this connecting member and bites into a surface of the rib when the connecting member is connected to the rib.
In this case, the thin wall portion is ruptured as the airbag inflates. Accordingly, the cover body is rotated and opened into a cabin with a portion near a root of the rib as a hinge center. At this time, an upward pulling-up force is applied to the cover body. However, since the projection of the connecting member and the rib of the cover body are connected to each other, such that the projection bites into the rib, no cover body is separated from the connecting member so that scattering of the cover body is reliably prevented.
Next, for example, an embodiment of the present invention reside in a method for producing the panel for the airbag of an automobile.
Namely, as in an embodiment of the present invention, a method for producing a panel for an airbag of an automobile includes integrally molding a cover body, made of a synthetic resin, with a main body, made of another synthetic resin, the method comprising the steps of:
preparing a thermoplastic material having compatibility as the synthetic resin forming each of the main body and the cover body;
arranging a movable core in a male or female die as a mold;
interrupting a portion between a first cavity portion for forming a first member and a second cavity portion for forming a second member by allowing the core to project and contact an opposite die;
injecting a material of the first member into the first cavity portion;
forming a communicating portion between the first and second cavity portions by allowing the core to retreat; and
injecting a material of the second member into the second cavity portion and the communicating portion so that an overlapping portion of both the first and second members is formed and adhered and both the first and second members are made integral with each other.
The key feature of this producing method is that the main body and the cover body are integrally formed by injection molding by the following construction and method.
Namely, the synthetic resins forming both the members are set to be compatible with each other. In the meantime, the movable core is arranged in a male or female die for the injection molding. First, this core is projected and comes in contact with the opposite mold. Thus, the portion between the first and second cavity portions is interrupted, and the material of the first member, as a material of either of the main body or the cover body, is injected into the first cavity portion such that no first member flows into the second cavity.
In a subsequent second step, the core is retreated so that the first and second cavities are communicated with each other, and the material of the second member is injected into the second cavity portion. Both the members are made integral with each other by forming an overlapping portion of both the members in the communicating portion of both the cavity portions and adhering the overlapping portion utilizing compatibility of both the materials.
As mentioned above, in this producing method, the main body and the cover body can be made by one injection molding by a two-color molding method so that no fixture for connecting both the members to each other is required and no connecting step is also required. Accordingly, the number of producing steps and cost can be greatly reduced compared with a conventional product in which the main body and the cover body are separately formed.
Further, it is preferable that a projecting portion, of a predetermined width, is continuously formed along a boundary portion of both the cavities in the opposite mold in a contact portion of the core and the opposite mold. It is also preferable that a groove portion, having a closed curve shape of the predetermined width, is formed in a boundary portion of the first and second members. It is further preferable that a thin wall portion ruptures at an operating time of the airbag and a non-thin wall portion, unbroken at the operating time of the airbag, are formed along the groove portion of the cover body in a single continuous line shape or a shape of plural continuous lines.
In this case, the projecting portion, projected in a larger extent than its peripheral portion and having a relatively narrow width, is formed in the mold opposed to the core so that the groove portion, having a closed curve shape, can be easily formed. In a position continuously connected to the groove portion, a thin wall portion, thinner than the thicknesses of wall portions in other positions, can be easily formed by forming the groove portion. Since the thin wall portion is ruptured earlier than its peripheral portion when pressure is applied to the thin wall portion, this thin wall portion becomes a ruptured portion of the cover body when the airbag is operated.
The boundary portion of the cover body and the main body (first and second members) can be easily observed by the groove portion. Further, an excellent appearance in design can be also given depending on a groove shape.
When the thin wall portion is ruptured and the cover body is opened, it is preferable that the shape of a line forming the thin wall portion and the shape of a line forming the non-thin wall portion are set onto the cover body such that the non-thin wall portion becomes a rotating central axis of an opening movement of the opening portion of the cover body.
In this case, when the airbag is operated and the thin wall portion is ruptured, a rotating moment, with the non-thin wall portion as a rotating center, is applied to a broken cover portion and the cover body is easily opened. Accordingly, resistance to swelling-out of the airbag is reduced and the airbag can be easily swollen out.
A combination of thermoplastic material having compatibility is constructed by a combination of polypropylene resin forming the main body and olefin thermoplastic elastomer (TPO) forming the cover body and the like.